Shaykh Ahmad ibn Ahmad Shamlaan (hafithahullah) mentioned thirteen mannerisms that are to be observed for the one eating the Sahoor:

Sincerity of the intentions

Saying Bismillah when one is about to eat, eating with the right hand, and eating with that which is closest, based upon the hadeeth of Umar ibn Abee Salmah

Gathering together upon the food. Indeed in that there's a blessing.

Not being wasteful in the meal and praising Allah for it.

The meal is from lawful wealth. Indeed it is stronger for (carrying out) the act of worship. Indeed Allah is good and He only accepts that which is good.

Having concern for the (proper) time (regarding the suhoor).

Seeking the forgiveness and making supplication in abundance during the time of as-Sahar (last part of the night shortly before the break of dawn). For indeed it is a blessed time (period).

Give Sadaqah during that time and being diligent to be one who aids the one who has the ability to fulfill the fasting by feeding him the Sahoor.

Washing the mouth good along with the usage of the Siwaak. This is in order that the traces of the food do not remain in the mouth which will cause the one fasting doubt if it was to overwhelm him and enter down his throat.

Waiting after the eating of the Sahoor for the purpose of performance of the dawn prayer. How praise worthy it is if the person was to go to the Masjid and wait for the prayer. Indeed that is stronger for him upon that (matter of praying the Fajr prayer on time). This is the case especially when many from amongst the people stay awake during the nights of Ramadaan up until the (time for) Sahoor. They eat the Sahoor then lay down. As a result of that, sleep overcomes and they miss the prayer. It's possible that the person doesn't get up until after the sun rise and some mid-day.

Taking the food that is suitable for the condition of the one fasting. Like eating the dates along drinking milk and that which is similar to it.